The present invention concerns a sanitary napkin excellent in absorbing and holding the menstrural blood and in preventing the exudation and the leakage of the menstrural blood once absorbed therein as well as excellent in disintegrating in water.
The performances required to a sanitary napkin are (1) an ability of absorbing and holding the menstrural blood in a large amount (excellent in absorbing and holding), (2) an ability of preventing the exudation and the leakage of the menstrural blood once absorbed therein (excellent in preventing the exudation and the leakage of once absorbed blood) and (3) a property of collapsing in water by disintegration and dispersion in water (collapsing property in water) not to cause the clogging of the drain-pipe and the disturbance of the function of the purifier of excreta when the napkin is thrown into the stool in a flush toilet including the purifier of excreta.
However, the hitherto proposed or practicized sanitary napkins do not necessarily fulfill all the performances (1) to (3) above-mentioned.
For example, hitherto a sanitary napkin comprising covering an absorbing layer of the menstrural blood formed of a mixture of crushed pulp and sanitary cotton and lined with a pile of a sheet of water-proof paper and a water-proof film consisting of low-density polyethylene with a non-woven cloth which is dispersible in water, or another sanitary napkin (Japanese Utility Model Publications 44318/74, 44319/74 and 44000/75) comprising covering the above-mentioned absorbing layer of the menstrural blood lined with the sheet of waterproof paper and a film containing more than 50% by weight of polyvinyl alcohol of an average degree of saponification of 89.5 to 98.5 mol% with a covering material dispersible into water in the presence of an aqueous solution of polyvinyl alcohol has been proposed, however, since these conventional sanitary napkins do not absorb a large amount of the blood and do not sufficiently prevent the exudation and the leakage of the once absorbed blood, they are not satisfactorily practicized.
Accordingly, the purpose of the present invention is to offer a sanitary napkin excellent in absorbing and holding the menstrural blood and also excellent in preventing the exudation and the leakage of the once absorbed blood as well as excellent in disintegrating in water.